Safety appliance for movable parts

ABSTRACT

An appliance which, through motor-driven operation, is movable toward a closing edge, in particular, for use with window regulators and sliding roofs of automotive vehicles. For this purpose, the number of revolutions of the motor is permanently detected, with the number of revolutions of the motor being measured in successive measuring intervals. The number of revolutions is to be a measure of the force acting on the pane. Respectively the last four measured values are detected in a sliding register and are subjected to evaluation. For this purpose, first a start-up value is detected. The start-up value respectively is the third last measured value n i-3  if the difference D between the current measured value and the third last measured value does not exceed a predetermined differential threshold D max . For, in that case, the start-up value remains unchanged. Subsequently, the difference A is formed between the start-up value and the current value n i . If the latter is above a predetermined response threshold A max , the anti-clamping system responds. This means that the driving motor is turned off and, optionally, is inverted in the direction of rotation thereof. More specifically, the forces acting on the pane are successively integrated from one measured interval to the next as long as there is some sort of increase from one measured interval to the next. As soon as the integration value A reaches the response threshold A max , the anti-clamping system responds. In this way a sensitive and rapidly responding protection against clamping is realized, wherein error signals based on fluctuations in the frictional resistance of the pane guide are suppressed.

TECHNICAL FIELD

The invention is concerned with a safety appliance for manipulatableparts which, through motor-driven operation, are movable toward aclosure edge, in particular, for use with window regulators and slidingroofs of automotive vehicles.

BACKGROUND OF THE INVENTION

Electromotive drives for windows and sliding roofs are beingincreasingly assembled in automotive vehicles to relieve the driver orfront-seat passenger from the effort involved with opening and closing awindow or a sliding roof. Although these drives are an attractivefeature, they must be prevented from closing or opening under certainconditions.

It has, therefore, been previously suggested to provide safetyappliances intended to prevent items or parts of the body from beingclamped. For example, DE-OS 37 36 400 sets forth that it is known tomonitor the consumption of current and/or the number of revolutions ofthe driving motor or to use pressure- or temperature-sensitive sensorsresponding and generating a signal if foreign matter is present duringthe closure process, between the window edge and the closure edge of theframe.

Both the number of revolutions and the consumption of current of thedriving motor are means for indirectly measuring the forces acting onthe sliding member. Apart from the difficulty directly measuringabsolute values, the problem involved with safety devices based on theevaluation of absolute quantities resides in determining the responsethreshold at which the anti-clamping system is to respond. A low-levelthreshold may cause the switch-off means to respond even if there is nodanger for an item to be clamped. For, the lateral guide of the pane orsliding roof also exerts forces on the pane that vary in accordance withthe ambient conditions. For example, at low temperatures, running of theguide is substantially less smooth. If the threshold is high, theanti-clamping means will respond be too late.

It has already previously been suggested (European patent applicationNo. 0442388) not to determine the absolute quantity but rather thechange from one measuring interval to the next. However, even then it isdifficult to determine the response threshold. If it is set too small,the switch-off device may become operative upon the occurrence of usualfluctuations in the resistance of the pane guide. If the threshold isset too high it may be that the anti-clamping system does not respondonce a soft item is clamped because the force during squeezing togethera soft body, from one measuring point to the other, only irrelevantlyincreases with the consequence that the anti-clamping system does notrespond although very high forces act upon the clamped-in item whichforces have, however, been built up in small increments.

According to the description of the state of art the problem encounteredresides in providing a safety appliance insuring a sensitive and earlyresponse which only occurs if an item is actually in danger to beclamped.

It is, therefore, suggested by the invention to provide a measuringinstrument detecting in successive measuring intervals a quantityrepresenting the operating force on the movable part. Moreover, anevaluator is provided determining the difference between the measuredquantity in a start-up interval and the measured quantity in a finalinterval, with the drive being switched off as soon as the differenceexceeds a response threshold. The start-up interval is defined in thatrespectively a quantity is measured in the measuring intervals betweenthe start-up interval and the final interval which exceeds the value ina preceding measuring interval by a predetermined amount, i.e. thedifference threshold. The evaluation pattern can be used irrespective ofthe absolute quantity actually detected. It can be the currentconsumption or power absorption of the motor or the number ofrevolutions of the motor. Also, the forces applied to the sliding membercan be directly measured.

The basic principle of the invention resides in that the changes in theforce, from one measured interval to the other, are integrated as longas a certain increase is achieved from one measured interval to theother. If the increase in force drops below a predetermined value, theintegration is restarted at zero.

In this manner, fluctuations in force that are not caused by clamped-initems will not be registered. Temporary interferences, may start anintegration which, however, does not accumulate until the thresholdvalue is reached. Generally, the integration will discontinue after afew steps. However, if the force grows slowly but steadily, as is thecase, for example, with soft clamped-in items, the drive is discontinuedas soon as the integrated value reaches the threshold. However, asalready minor changes in force are included in the integration at thebeginning of the clamping process, the safety appliance will respond intime.

An easily detected quantity representing the operating force is thenumber of revolutions of the driving motor. The same is, in turn, mosteasily detected in that the circulation period per revolution of thedriving shaft of the motor is determined.

The evaluator, advantageously, contains a slide register comprisingregister numbers 1 to 4, with No. 1 containing the current value andNos. 2 to 4 the preceding measured quantities.

The actuator contains another register for the start-up measuredquantity which is overwritten by the value from the No. register 4 ofthe slide register only, once the difference between the values ofregisters Nos. 4 and 1 is less then a predetermined differentialthreshold value.

Subsequently, the difference between the value in register No. 1 and thevalue in the register for the start-up measured value is formed. If thedifference exceeds the threshold value, the anti-clamping system willrespond.

In addition, it has proved to be advantageous once the values in theslide registers, prior to evaluation thereof, be subjected tomodification resulting in that the value is flattened to a certainextent. As a rule, it is sufficient to change the value in register No.3 to the effect that, initially, the peak value is determined inregisters Nos. 1 and 2. Once the value in register No. 3 is between thesaid peak value and the value in the No. 4 register, it will not bemodified. If it is outside the said range of values, in special cases,the average value between the value in register No. 4 and the peak valueis written into register No. 3.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic representation of a window lift mechanismcommonly found in automobile doors.

FIG. 1B is a logic flow diagram showing the filtering algorithm of thepresent invention.

FIG. 2 is a logic flow diagram showing the anti-clamping algorithm ofthe present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

One form of embodiment of the invention will now be explained in closerdetail, with the required computing steps being shown in the two logicflow diagrams of FIGS. 1 and 2, with the part to be moved, e.g. a windowof a private passenger car, and the driving motor, not shown.

A sensor is provided on the motor, which supplies one pulse perrevolution of the armature spindle to the control system. The sensorincludes two outputs the signals of which are staggered by 90°, with oneof the said outputs of the sensor leading to an interrupt input of thecontrol system. If, during a flank, the level of the second sensoroutput on the interrupt input is contemplated, this will enable thedirection of revolution of the motor to be identified. By counting thepulses on the interrupt input, under consideration of the direction ofrevolution, the present position of the pane can be determined. To thatextent it will be necessary for the counter to be set, in apredetermined position of the pane, to a synchronous value.

In this way, the position of the pane, depending on the layout of themotor gear, can be determined with a precision of about 2 to 3 mm.

The total closing distance 24 of a side window of an automotive vehiclecorresponds to approximately 200 to 300 pulses. A synchronous value isset once the pane blocks on the upper stop. The synchronous value isselected slightly larger than the computed number of pulses across theclosing distance of the pane. With a pane, the closing distance of whichcan be represented by 226 pulses, the synchronous value is set, forexample, to 250.

The circuit hereinafter described by which a protection against clampingis insured, is activated only as long as the pane is not moved into theclosing fold of the closing edge of the frame. In the example ofembodiment this corresponds to a pulse value of 242.

The number of revolutions of the motor is determined by identifying thetime between two successive pulses. The time range to be determined isbetween about 10 and 100 milliseconds, corresponding to a number ofrevolutions of between 6000 and 600 revolutions per minute.

The evaluator provides a slide register with locations Nos. 1 through 4.A new measured value entered as the number of revolutions into locationNo. 1 is detected in each cycle, i.e. with each revolution of thedriving motor. Allocations of the other registers are previouslydisplaced by one register. The four registers thus represent the lastfour measured values.

Prior to a further evaluation first the measured values are filtered orcorrected, respectively, on register No. 3. The way of filtering is showin FIG. 1.

The actual measured value is designated by n_(i) which is filed inregister No. 1. The indexed indications I-1, I-2 and I-3 relate to thepreceding measured values filed in registers Nos. 2 to 4. The computingpattern contains a first branch for checking whether the value n_(i)exceeds the value n_(i-1). Depending on the result of such a check, thevalue n_(i) or n_(i-1) is filed in an intermediate register whichhereinafter is designated by n_(g). Accordingly, n_(g) is the higher ofthe two values n_(i) or n_(i-1). In a next two-phase step it is checkedwhether the measured value n_(i-2) is between n_(g) and n_(i-1). Forthat purpose it is first checked whether n_(g) exceeds n_(i-3) ; if so(left-hand branch), it is checked whether n_(i-2) is less than n_(i-3).In that case, the value n_(i-2) is replaced by the average value ofn_(g) and n_(i-3), and is overwritten in the No. 3 register.

If the result of this check is that n_(i-3) exceeds n_(g) (right-handbranch), it is checked whether n_(i-2) is less than n_(g). In that case,the average value is formed as described. Otherwise, the value n_(i-2)remains unchanged and No. 3 register is not overwritten.

Activation of the anti-clamping system is according to the algorithm ofFIG. 2. For this purpose it is necessary that a synchronous value is setfor determining the position, that the driver actuates a correspondingbutton and that at least four values for the number of revolutions havebeen detected. The anti-clamping system is activated only in the centralarea of the window closing distance. The first 50 mm, measured from thebottom stop, are covered with no activation of the anti-clamping system.Deactivating of the mechanism in these areas, initially, results in highnumbers of revolution rapidly dropping thereafter. The decrease in thenumber of revolutions would pretend an increase in force causing theanti-clamping system to respond by way of inadvertence. Also a shortdistance ahead of the upper stop, the anti-claming system isdeactivated. This deactivation is present because the pane, over thisdistance, runs in a fold requiring high operating forces. If theanti-clamping protection system were deactivated, the window would bere-opened.

A response of the anti-clamping system means that first the motor isimmediately switched off and after a delay of 50 milliseconds the paneis moved by about 50 mm in the opening direction to release the item. Inany case, an opening of at least 200 mm should be released, i.e. thedistance between the upper edge of the pane and the upper folding edgeshould amount to 200 mm.

As previously explained, the number of revolutions of the engine ismeasured, which, as is well known, is in a linear relationship with theoperating force of the engine as long as a constant supply voltage forthe engine is available. This can be assumed over the duration of aclosing operation.

The anti-clamping algorithm comprises the following steps: The locationsof the register are displaced by respectively one location. Then a newcurrent value is read into register No. 1. Subsequently, filtering isperformed as previously described and then the actual increase in forceis determined by forming the difference between the values in registers1 and 4. These are the values of n_(i) and n_(i-3). Throughmultiplication by an engine-specific constant K, a current differentialvalue D of the force is obtained. This value is compared to thedifferential threshold D_(max) which in the example of embodiment isabout 10N. If the rise is below the threshold value, the value n_(i-3)is written into an intermediate register which hereinafter is designatedby n_(alt). If the rise is above the threshold, the intermediateregister is not changed. Hence, the intermediate register always storesthe measured value which is present at the beginning of a rising forcecurve. It can be called the "start-up value". Then the difference isformed between n_(i) and n_(alt). This value is also multiplied by themotor-specific K; a force value A is obtained. If the value A is above aresponse threshold value A_(max), the anti-clamping system responds. Theresponse threshold in the example of embodiment is A_(max) =30N.Otherwise, the computing pattern restarts by displacing the locations ofthe register and by putting in a new measured value.

We claim:
 1. A method of manipulating movable vehicle appliances throughmotor-driven operation, comprising the steps of:(A) measuring first andsecond values representing an operating force on a movable vehicleappliance, (B) measuring third and fourth values representing theoperating force exerted on the movable vehicle appliance, (C)determining a difference between the first and second measured values togenerate a first interval value, (D) determining a difference betweenthe third and fourth measured values to generate a second intervalvalue, (E) determining a difference between the second interval valueand the first interval value to determine if it exceeds a predeterminedthreshold, (F) ceasing movement of said movable vehicle appliance if theresult of step (E) is positive.
 2. The method of claim 1 for a drivingmotor having a revolving driving shaft, further including the step ofmeasuring a number of revolutions of the driving motor.
 3. The method ofclaim 2, further including the step of determining a rotation time perrevolution of the driving shaft of the driving motor.
 4. The method ofclaim 1, further including the steps of storing said first, second,third and fourth values in a slide register having first, second, thirdand fourth registers.
 5. The method of claim 4, further including thestep of modifying the values stored in the slide register.
 6. The methodof claim 5, further including modifying the values in the slide registeraccording to a predetermined regulating pattern.
 7. The method of claim6, further including determining which of the first and second registerscontains the largest value and then comparing that largest value to thevalue in the fourth register.